Blueberries have all the qualities of brilliant garden plants. Often seen on farms or in rural landscapes, blueberries have a place in almost every garden. Certainly, our urban spaces could do with more of these native, valuable shrubs.
Perhaps by taking a brief survey of the qualities of Vaccinium that makes it such a great candidate for the ornamental garden, describing and hopefully demystifying the core aspects of growing blueberries, and maybe even throwing in a little history, I can convince you to grow blueberries as ornamental shrubs.
Growing blueberries as ornamental shrubs
Blueberries are generally easy to grow as long as you select a species that does well in your region. Blueberries are deciduous shrubs native to large swaths of the eastern United States. The silvery-green foliage is gorgeous.
The fall color is nothing short of breathtaking. Blueberries are native.
There are species of blueberries that are winter hardy well into Canada and others that can handle the hottest summers of the Deep South. I have not yet mentioned the actual blueberries themselves. It’s always a race against the birds when it comes to the fruit anyway.
You can protect the blueberries from birds with nets but I don’t bother. It is certainly understandable that any gardener would wish to protect their blueberries. My propensity to forego nets is a combination of laziness and perspective.
You can grow lowbush blueberries as groundcovers, and highbush blueberries in the border or as hedges. The environmental impact of blueberries is nothing but positive, as they provide cover and food for birds and insects for months. While the shrubs are in flower, the bees arrive for the early spring supply of nectar.
You can grow blueberries in containers. Blueberry shrubs are generally deer resistant, although the deer will nibble on the berries.
There are different types of blueberries best suited to the different geographies of North America.
For most of my gardening life, I’ve seen highbush or rabbiteye blueberry shrubs for sale. I live in Georgia.
Who will get to these blueberries first?
The difference between lowbush, highbush, and rabbiteye, and half-high blueberries
There are actually five main groups of blueberries: lowbush, northern highbush, southern highbush, rabbiteye, and half-high.
Lowbush blueberries, Vaccinium angustifolium, are native to the northeastern United States and Canada. When I think of lowbush blueberries, I think of Maine. Also called wild blueberry, lowbush have smallish, yet incredibly sweet fruit. Lowbush blueberry shrubs also don’t grow very large, less than a couple of feet tall. They like to sprawl and are renowned for their sweetness. Lowbush blueberries are hardy to zone 3.
Highbush blueberries, Vaccinium corymbosum, grow larger than lowbush varieties, to eight feet tall. Their berries are plumper than the lowbush varieties. There are northern and southern highbush blueberries. You can find Vaccinium corymbosum growing natively from Canada to Florida and west to Texas.
Rabbiteye blueberries, Vaccinium ashei, earned their name because the fruit turns pink before ripening. Naming a blueberry after a domestic white rabbit’s pink eye color frankly seems weird but it adds to the story for sure. Vaccinium ashei’s native distribution is restricted to the Deep South. Also, rabbiteye blueberries are considered low-chill. Chill hours are explained below.
Half-high blueberries are hybrids created by crossing northern highbush and wild blueberries. They tend to be compact and low-growing. Half-high have a reputation for excellent tasting blueberries and are extremely cold-hardy. Due to their compact growth habit, half-high blueberries make perhaps the best choice of all as ornamental shrubs.
Choose blueberries that will do well in your geographic region.
Local nurseries will stock appropriate blueberry varieties for your area.
Perhaps the most vexing thing about growing blueberries is choosing the species for your garden. Lowbush blueberries are grown in the northern U.S., and rabbiteye blueberries are grown in the South. You can grow highbush blueberries across a wide geographic region.
What determines a blueberry shrub’s suitability for your region? It comes down to winter hardiness and the all-important chill hours metric.
Chill hours and blueberries explained
Chill hours are the number of hours of winter temperatures 45°F or below. For the best harvest and growth the following season, it is important blueberry shrubs receive an adequate number of chill hours. Whereas a rabbiteye variety such as Brightwell may only need 400 chill hours, some northern cultivars can require over 1000 chill hours.
If you wish to delve into the science of growing blueberries, it is substantial and rewarding. There are a lot of different blueberry varieties to research, and data is collected for the number of chill hours across the United States. You can easily check AgroClimate chill hours for your area simply by entering your zip code.
AgroClimate is a beautifully executed climate data center that is part of a consortium of eight major universities, including my alma mater, the University of Georgia.
Unless your interest in blueberries veers towards serious, you are generally safe purchasing varieties offered by your local retailers.
Do blueberries need cross-pollination?
Cross-pollination is the intermingling of pollen from different varieties of a plant. The bees and wind are mostly responsible for cross-pollination. Many blueberry cultivars are self-pollinating. Thus, why the seemingly universal recommendation to buy different varieties? First, you safely remove having to worry about whether your blueberry is self-fertile. I suspect many local retailers just assume all blueberries require self-pollination, which is not the case.
Many of the half-high cultivars are self-fertile, a critical detail considering other blueberry varieties do not flower at the same time as the half-high varieties.
However, cross-pollination is important to blueberries. You will have better crops and larger fruit. To ensure cross-pollination plant different varieties within six feet of each other.
Also, be aware there are early, mid, and late season blueberries. It is important you select blueberries to cross-pollinate that bloom at the same time.
Blueberries uniformly like acidic soil in the range of 4.0-5.0. It is worth having your soil tested for pH where you intend to plant your blueberries. Kits are sold online, at nurseries, and at places like Home Depot. You can also use vinegar and/or baking soda to test soil pH.
Should your soil pH need to be adjusted, there are compost mixes for azaleas and rhododendrons that will improve soil quality while lowering pH into the desired acidic range. By the way, blueberries are related to azaleas and rhododendrons. Adding peat moss is another time-honored method of lowering pH and you can find it in most garden stores.
Adding oak leaves and pine needles and such in an attempt to lower your pH will not work. Don’t bother.
Blueberries produce fruit by the second year, but it can take up to six years to reach full potential.
Blueberries prefer full sun and well-drained fertile soil. You can grow blueberries in shade by the way but berry production will be compromised and the shrub may become leggy. The only negative thing I can say about blueberries is they can be a bit unrestrained and wayward in their growth habit. Don’t encourage this by skimping on the hours of sunlight available to the plant.
Also, don’t skimp on soil preparation. We have clay soil in Georgia and it needs to be amended to arable consistency. Ideally, we want a loose, rich soil that has plenty of air pockets and drains well. In areas with heavy clay, you risk root rot even if the soil is amended well.
Do not plant the shrub any deeper than ground level, good advice for planting most shrubs. In any area of the country with heavy clay, you can plant blueberries in raised beds or even raised mounds.
Like the azaleas and rhododendrons to which it is related, Vaccinium has shallow roots. Prepare soil to 24″ deep and wide. Rabbiteye and highbush blueberries can get big, to eight feet tall. Plant them five or six feet apart. Mulch 2″-3″ thick with pinestraw. If you weed around the blueberry shrubs pull the weeds by hand. If you hoe the weeds, be careful, as you can easily damage the shallow growing roots.
A brief history of 20th-century blueberries
Blueberries have only been in commercial cultivation for a relatively short period, a little over a hundred years. Two people, Elizabeth Coleman White and Dr. Frederick Vernon Coville, are largely responsible for every blueberry you and I have ever eaten.
Elizabeth Coleman White grew up on her father’s cranberry farm in Whitesbog, New Jersey. White and her father, a Quaker, used to eat wild blueberries during their walks in the woods near the farm. According to White’s writings, the pine barrens of New Jersey were home to some of the best highbush shrubs around. As she reached adulthood, Coleman considered what it might take to turn blueberries into a commercially viable crop.
Meanwhile, in New Hampshire, Dr. Frederick Coville was doing his own work with regards to Vaccinium. It was Dr. Coville who discovered why wild blueberries did not perform well when transplanted out of their native habitat into garden settings. Unsurprisingly, it was the pH of the soil. Dr. Coville correctly ascertained that blueberries need acidic soil, conditions not often found in the vegetable patches of the average home garden.
There was another product of Dr. Coville’s work, a report he wrote outlining his research into the acidic-loving nature of Vaccinium. It was from this report that White became aware of the efforts of Dr. Coville.
Dr. Coville was an impressive guy. He served as honorary curator of the U.S. National Herbarium at the Museum of Natural History, as well as the chief botanist of the USDA. He was also director of the U.S. National Arboretum. Even with all of these achievements Dr. Coleman is perhaps best known for his work with Elizabeth Coleman White.
In 1911, the collaboration began, with White providing the land for the research. She paid the USDA to carry out research into blueberries on her farm. White herself collected dozens upon dozens of varieties for hybridization, offering to pay the locals for any collected shrubs that had large berries. The locals delivered, bringing over 100 bushes collected from the barrens. Those original shrubs where named after the person who collected them.
Dr. Coville cross-bred the collected shrubs, selecting the plants with the best berries for further breeding. The winners were reproduced from cuttings.
By 1916, White and Coleman debuted their first commercial crop. The goal was simple, to create large, uniform berries that were consistent in quality and taste.
Over a hundred years later, Hammonton, New Jersey, a stone’s throw from the old Whitesbog farm, is the blueberry capital of the world. Blueberries are grown commercially throughout the United States, thanks in part to the development of blueberries capable of growing in the heat of the southern states. In winter, we eat blueberries grown in South America. In 2016, 690 million pounds of blueberries were brought to market. The U.S. is by far the largest producer of blueberries. In 2017, the United States exported 58.9 million pounds of blueberries.
All this from Whitesbog, New Jersey.
|Of note||choose blueberries according to the region you live in – the shrubs are generally deer resistant, although deer may nibble on the berries – beautiful fall color|
|Soil quality||rich, well-drained|
|Suggested use(s)||cottage gardens, mixed borders/perennial beds, native collections|
|Hardiness zone(s)||3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b|
|Deciduous or evergreen||deciduous|
|Flower color||pink, white|
|Bloom period||mid to late spring|
|Exposure||full sun, afternoon shade|1 1